1. Field of the Invention
The present invention relates to ratchets and, more particularly, to ratchets having a pawl for securing a cord against a spool.
2. Description of Related Prior Art
Ratchets of various types have been in existence for decades. The most common types of ratchets include a spool about which a strap or webbing is wrapped. A pivotable lever in engagement with sprockets attached to the spool can cause rotation of the spool in a first direction to wrap the webbing about the spool. A pawl or sliding member engages the sprocket to prevent rotation in the second direction whereby unwrapping of the webbing is precluded except upon release of the pawl or sliding member from the sprocket.
A second type of ratchet is used in conjunction with a rope. It includes a spool formed by a pair of facing discs having protrusions on the facing surfaces of the discs to frictionally engage the rope. The rope is wrapped about one-half of the spool. By pulling on the free end of the rope, the spool is caused to turn in one direction to provide tension to the other end of the rope. Slippage of the other end of the rope in the other direction is precluded by the frictional engagement between the rope and the protrusions of the faces of the disc. A spring-loaded pawl precludes rotation of the spool in the other direction. By pivoting the pawl out of engagement with the spool, the rope is free to cause rotation of the spool in either direction. U.S. Pat. Nos. 6,068,242, 6,092,791, and Des.362,614 are representative of ratchets of this type and are incorporated herein by reference.
The major distinction between these two types of spools may be categorized as follows. In the first type, slippage of the webbing from about a rotatably locked spool is prevented by the friction attendant layers of wrapped webbing; in some embodiments, the free end of the webbing extends through a diametrically oriented slot in the spool.
In the second type of ratchet, the friction between the rope and the protrusions on opposing faces of the discs forming the spool create sufficient friction and compression of the rope therebetween to preclude slippage.